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(No Model.) y E. H. MID-DLETON.

'SCREW JACK.

- No. 292.567. Paramaha. 29.1884.

Iig-.1. 1335.2.

wn'NEssi-:s: l I i 'INVENT R: J-fwf/g d I n 'A- Y l" Bv l f" Unrrnn ASTATES"iPi/rrniarr1]()1rrcra EDWARD H. MIDDLnroN, or PHILADELPHIA, rENNsYLvANLx.

SCREW-JACK.

irzcrrrcnirN forming'part of Letters Patent No. 292,567, dated Januavy 29, 1884.

Application filed May 7,188.3. (Nomodel.) i

Y sponding parts in the several figures.

My invention relates to improvements in a screw-jack in which the lifting-bar is operatcd by a worm and worin-wheel, whereby said bar ismoved with great power and uniforni ity and other advantages will be presented, as hereinafter set forth'.

' Referring to the drawings, A represents the box or stand of the jack, and B the liftingbar thereof, one side of said bar being toothed, constituting a rack, as at a. On the outer side of the stand is mounted a worm, C, which engages with a worm wheel, D, likewise mounted on the stand, it being noticed that the-shafts E F of the worm and worm-wheel extend at a right angle to each other, the

Ashaft E being mounted on a boss, E', cast with the stand, and the shaft F being mounted on bearings F F", the bearing F being cast with i the stand, and the bearing F being bolted to said fixed bearing F. v

- To the shaftF of the worin-wheel is keyed or otherwise secured a pinion, G, which en -V ters an opening in the stand A, and engages with the teeth of the rack portion of the bar B. The shaft E of the worm is squared for theengagement of a crank-handle, H, so that by the operation of the latter said worm is" rotated, the effect whereof is the rotation of the worm-wheel and pinion, which in one di rection raises the bar B, and in the other di In lieu of 'a crank-handle, l may employ lever provided .with a pawl or dog, and connect with the shaft E a ratchet, so that the latter may be operated where it is inconvenient to employ a crank-handle.

It will be seen that by means of the worm and worin-wheel, when the jack is in service, considerable power maybe imparted tothe pinion G and exerted on the bar B, whereby the load may be raised with ease, the operation being uniform,avoiding abruptness and the liability to break the teeth of the differ ent gearing. Furthermore, the pinion is prevented from rotating in reverse order, so that the `load cannot cause the bar to descend, unless the handle or lever is properly turned; andiin all cases the operation of the jack is comparatively. noiseless.

ings of the shafts are outside of the'stand, so that the Worm, wor1n-wheel, and pinion and the shafts thereof may be readily applied in position, lubricated, and removed,when required, the parts shown bolted to the stand being the small bearing-pieces F, the other bearings, F E', being cast solid with the stand, thus making a strong and simple screw-jack, and reducing expense in the manufacture of the saine.

In cases whenv the collar J is-too high for taking hold of objects, a foot-lift, J, is provided, the same having its horizontal part at or near the bottom of the stand when the lifting-bar is at its lowest position, said foot being connected with said bar so as to rise and fall therewith. In-order to permit said footlift .I to be moved around the stand, it is connected with the swiveled collar J at the top Fig. 3. Y

Having thus described my invention, what I claimas new, and desire to secure by Letters Patent, is-A l. l'Ihe stand, in combination withfa rackbar, B, )inion G, aworm, C, a wormif 'wheel, D, and shafts E F, said stand having "cast with provided with a removable bearing, F, the lpinion and' wormwheel being fixed to the same shaft,F, and both shafts E F being mounted outside of the stand, substantially as and for the purpose set forth.

2. A screw-jack consisting of the stand A,

Again, the bear-v of the rack-bar, as most plainly shown inl it a horizontal boss, E, and bearing F', and

the removable bearing F, the lifting rackadapted to be moved around the stand, sub- 1o with boss E', and bearing` F, cast therewith, pending from and secured to said collar, and

bar B, the pinion G, 'che Worm C, the wornlstanti ally as and for the purpose set forth.

wheel D the shafts E F, and a foot-lift con- 1 4, 5 nected Wth said bnr, substantially as and for i DDXVRD H' MIDDLDTO the purpose seb forth. \\'itnossos:

3. In a screw-jack, a swiveled collar on the JOHN SHALLCROSS, lifting-bar, in combination with a foot-lift dei GEORGE HUNTEN. 

